That having been said, it doesn't mean that exercises where the muscle is under stretch aren't effective. They do increase the sensibility of the IGF-1 receptors. And there is this mechanical saying that goes" "the muscle being stretched the most (in a movement) is the muscle recruited the most".
However lifts that put the muscle in a greater stretch will not make the muscle more separated.
Furthermore, I do not think that "quarter" squats from pins (you used that in your example) should be used as a main exercise to build muscle.